Airports around the world are under pressure to improve environmental performance inside the terminal, on the runway and in the air. Perhaps less well known is the fact that the aviation industry is inadvertently standing in the way of one of the world's most promising renewable energy sources: wind power.
A technical issue that has emerged over the last few years has been setting wind farm developers and airport operators against one another. Groups of wind turbines can appear as aircraft to air traffic control (ATC) radar systems, creating cluttered zones and making it difficult to track planes flying over wind farms.
This safety concern is costly and time-consuming for airports, which must spend time disputing wind farm developments.
This deadlock is also a major obstacle to the development of new wind farms, especially in countries like the UK, where development space is limited and airspace is incredibly crowded. The UK's Department of Energy & Climate Change has noted that two thirds of UK wind farm applications in 2010 were subject to radar interference-related objections from the aviation sector. Even in larger countries, radar interference is holding up wind farm development. In the US, for example, it has been estimated that 10GW of wind power has been delayed or abandoned because of radar concerns.
Technical fixes for this problem have so far been ad hoc and temporary in nature, but now UK company Aveillant, a spin-off of Cambridge Consultants, is seeking to solve the problem permanently with its holographic radar technology.
We spoke to Aveillant's general manager Craig Webster about the new solution and the company's ambition to stamp out this persistent problem for good, for the sake of airports and wind farm developers alike.
Chris Lo: With wind farm development building momentum, do you think radar interference will be a growing problem for the aviation industry?
Craig Webster: At the moment, airports are objecting to them and being drawn into public inquiries, so there's an awful lot of time and effort being expended.
It's one of the complications with this particular issue. The debate's being fought out in the planning departments and the courts, it's the planning system that is the mechanism by which all the dialogue is happening. That's not particularly helpful, because you can only object to one wind farm at a time, so it's been very hard to find a mechanism to look at it in a more collective manner.
The main reason for the problem is there isn't an off-the-shelf technical fix for this. If there was, people wouldn't have to object to new wind farms.
CL: What are the technical options available to airports to combat radar interference?
CW: To the best of my knowledge, there is one. I would call it a terrain-masking infill. Whitelee Wind Farm in Scotland, the biggest in the UK, has a new radar that was procured as an infill.
That's located in Kincardine in the old power station on top of a little tower. That radar is placed in such an area that the terrain is in the way, so it can't see the turbines, and the data from that radar is then taken and combined with the data for Glasgow Airport.
That's what they use. It's a pioneer system, it was the first that I'm aware of. I'd call it a terrain-masking 2D infill.
But to get a system like that to work - and I am aware there are a couple of systems in the pipeline that are better - you need to have a convenient piece of terrain and it's very dependent on where the radar is and what the nature of the airspace around it is.
CL: What about Newcastle Airport, which is using a software patch as a short-term solution?
CW: What I think they have there is in a limited number of areas, you can have a "no track initiation zone". So I think they blank the radar and don't allow the trackers to initiate new tracks, which means that they coast through them, essentially.
But they're quite small areas. Indeed, Newcastle has been in public inquiries at least twice in the last two or three years defending its position with wind farms going up in Northumberland.
So it's taken up a lot of their time as well. I don't know whether that solution is temporary or not, but it's definitely limited. In other words, they can take a small amount of this and once that's done, they'll have to look for something else.
CL: Could you explain Aveillant's holographic radar technology and how it differs from other technologies in this area?
CW: One of the issues with the 2D infill is that you have two 2D radars and a radar measures the range of the aircraft. So if it's high up, the projection on to screen from two different radars will put the plane in two different places because the slant range is different.
So we've taken an entirely different approach. We're still using transmitters and receivers and we're still using technologies that clearly work, but we're configuring it in such a way that we have a three-dimensional radar for a start.
So we can deal with slant range errors with an infill patch, which can go near or in the wind farm, rather than the airport. So it's three-dimensional, we know exactly the height of the target and it's very easy for us to tell the primary surveillance radar exactly where the aircraft is, as if it were being seen by the primary radar itself.
The other thing is that we're constantly illuminating the area around the wind farm and we're constantly looking at the whole volume of surveillance all the time.
So we're not scanning, we're looking all the time with multiple beams and so on. We get an awful lot of information from that, and when we have that information, the difference between a turbine and an aircraft is like chalk and cheese. We can separate them very easily. It's that simple, really. We can actually see what's going on inside the wind farm, which is almost unheard of.
CL: How is your first-stage design contract with Glasgow Prestwick Airport (GPA) progressing?
CW: We haven't installed the system there yet, we're in the early stages of the contract. We've been contracted to do the first part of the system design, and that's gone really well.
The experience at Glasgow has been a bit different, because Glasgow Prestwick has been very active. Often an airport will tell a developer that they have to find a solution. But GPA made a very conscious decision to engage with the wind industry and with technologies to make sure they had a voice in the solution.
They've been very proactive and they've put a tremendous amount of resources behind it, even to the point where in many of the government panels and so on, there are staff members from GPA present.
They've been through all the technologies and came to the conclusion that the only technology which looked like it was going to offer the performance they required was a holographic radar. It needs to give the appropriate low-level coverage and the seamless integration.
At GPA we went through the system requirements and ran through part one of the safety case, keeping the Civil Aviation Authority and everybody else involved as well. That was the gist of the process, and I believe they're very happy with it.
CL: Do you think overcoming this particular problem could have an effect on wind farm development prospects around the world?
CW: That is absolutely our ambition. I came to this from Cambridge Consultants' clean technology campaign, so I was looking at technology for the renewable industry to help boost its growth.
We found this technology that fell between the renewable and the aviation industries. But that's why we have created the company, that's why we have invested and others have invested as well.
It's an international problem as well. It's come to a head in the UK, mainly because we've got a very limited landmass. We've also got a lot of air traffic, military and civilian. So this is our mission: to bring a product and service that takes this problem away.
We're looking at the international market. We're engaged with various processes in the US and we know if you comply with interoperability you're applicable in Europe. We're looking to export this UK technology everywhere we can.